The existence of a significant amount of electricity sources dispersed throughout the low-voltage distribution system could create a power system quite different to the one we are familiar with and creating it offers significant research and engineering challenges. Moreover, the electrical and economic relationships between customers and the distribution utility and among customers may take forms quite distinct from those we know today. For example, rather than devices being individually interconnected in parallel with the grid, they may be grouped with loads in a semi-autonomous neighborhood that could be termed a microgrid, a cluster of small (by the standards of current power systems, e.g. < 500 kW) sources, storage systems, and loads which presents itself to the grid as a legitimate single entity.